docs: def run(self, name, *args):
          """Run an action as specified by its name."""
          assert isinstance(name, string_types)
          # Resolve the alias if it is an alias.
          name = self._aliases.get(name, name)
          # Get the action.
          action = self._actions_dict.get(name, None)
          if not action:
              raise ValueError("Action `{}` doesn't exist.".format(name))
          if not name.startswith('_'):
              logger.debug("Execute action `%s`.", name)
          return action.callback(*args)